Now and then: Occasionally; sometimes. If you say that something happens now and then or every now and again, you mean that it happens sometimes but not very often or regularly. As in Josh does stop by the store every now and then, but I haven’t seen him lately.
中文释义：now and then相当于now and again，意思是时而；偶尔，用于表达出现频率少的偶尔发生的事情。同义词还有occasionally，on occasion。引申every now and then用于表示时常、经常发生的事情，用作状语，可以放在句首，也可以在句中。
EG.01: This section of the road is so narrow that there are bound to be traffic jams now and then.（这段路太窄， 交通有时不免堵塞。）
EG.02: Every now and then I like to walk along the beach and forget my problems．（我常常喜欢沿着海滩散步，有益于忘记我的烦恼。）